Sunday, July 10, 2016

How to work up hematuria

This topic was recently reviewed in Advances in Chronic Kidney Disease. From the body of the paper:

On finding a urine dipstick positive for blood, the test should be repeated after several days, to account for any transient causes of MH, such as physical activity, sexual intercourse, or menstruation. If the dipstick remains positive, urine microscopy should be performed to identify RBCs and to define their morphology (dysmorphic or isomorphic)..For our purposes, we define MH as 3 or more RBC/hpf. If no RBCs are visualized, patients should be evaluated for alternative causes of a positive dipstick, such as myoglobinuria. We agree with the CUA guidelines 2 and Huussen and colleagues, 35 who suggest that urologic imaging and cystoscopy may not be required if dysmorphic cells or RBC casts are seen, suggesting a glomerular etiology. Such findings should, however, prompt assessment of kidney function and urinary protein excretion. If the patient has a reduced GFR or proteinuria, referral to nephrology is warranted and a kidney biopsy should be considered. For those individuals with isolated glomerular MH, a clinician should assess these patients annually for kidney function changes and/or the development of albuminuria or proteinuria. If isomorphic RBCs are seen on urine microscopy, the clinician should confirm with the patient whether possible benign causes of MH such as recent physical activity or trauma, sexual activity, menstrual bleeding, viral symptoms, or urethral instrumentation may account for these findings. If a benign cause is present, a repeat urinalysis should be done in several weeks to ensure resolution. If the earlier mentioned causes are not identified, imaging of the GU tract is indicated. Although CTU has demonstrated the best testing characteristics, we emphasize the importance of limiting cumulative doses of radiation exposure, especially in younger individuals..alternative imaging modalities should be considered, including US or MR...

If no parenchymal lesion is detected on imaging, the clinician should assess the patient's GU cancer risk factor profile. If risk factors are present, they should be promptly referred to urology for cystoscopy. If a patient has no such risk factors, age should be considered before undergoing cystoscopic evaluation. We consider the evidence presented in the 2012 AUA guidelines inadequate to support cystoscopy for anyone with asymptomatic MH younger than 40 years. Patients with asymptomatic MH aged 50 years or older have sufficient cancer risk to warrant cystoscopy, regardless of risk factor profile. 6 For patients aged 40 to 49 years, the data are unclear; if no risk factors are present, clinical judgment for cystoscopy referral is advised.

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